Implement `-fvk-use-dx-layout` (#4912)

* Implement `-fvk-use-dx-layout`

Fixes: #4126

Changes:
* Added fvk-use-dx-layout
* Modified `HLSLConstantBufferLayoutRulesImpl` for correctness (ex: Array is always 16 byte aligned)
* Added kFXCShaderResourceLayoutRulesFamilyImpl and kFXCConstantBufferLayoutRulesFamilyImpl to handle fvk-use-dx-layout
* Added `ConstantBufferLayoutRules` to manage constant buffer rules
* Added `alignCompositeElementOfNonAggregate`/`alignCompositeElementOfAggregate` to handle forced alignment of composites for ConstantBuffers
* `StructuredBuffer` rules are mostly equal to `scalar` layout, not much was needed to be changed to support this behavior.

* seperate legacy constant buffer and how Slang does constant-buffer normally

* undo an addition

* remove accidental test

* Address review and fix

Address review and remove GLSL support since GLSL requires a seperate legalization (need to linearlize structs like with `legalizeMetalIR` to assign explicit offsets)

* comments

* remove aggregate and non-aggregate logic

We don't need this distinction for the logic

---------

Co-authored-by: Yong He <yonghe@outlook.com>

1 files changed, 73 insertions, 0 deletions

diff --git a/tests/spirv/tbuffer-dx-layout-1.slang b/tests/spirv/tbuffer-dx-layout-1.slang
new file mode 100644
index 000000000..c1f494497
--- /dev/null
+++ b/tests/spirv/tbuffer-dx-layout-1.slang
@@ -0,0 +1,73 @@
+//IGNORE_TEST:SIMPLE(filecheck=SPIRV): -target spirv -entry computeMain -stage compute -fvk-use-dx-layout
+
+// 'tbuffer' is not implemented for SPIRV targets currently.
+
+tbuffer Test
+{
+//SPIRV: Offset 0
+    uint v0;
+//SPIRV: Offset 4
+    float3 v1;
+
+//SPIRV: Offset 16
+    uint3 v2;
+
+//SPIRV: Offset 32
+    uint2 v3;
+//SPIRV: Offset 40
+    uint2 v4;
+
+//SPIRV: Offset 48
+    uint v5[4];
+
+// array always starts on a new register.
+//SPIRV: Offset 112
+    uint3 v6[2];
+//SPIRV: Offset 140
+// non-array can pack with a partially filled register
+    uint v7;
+
+//SPIRV: Offset 144
+    uint2 v8;
+
+// SPIRV: Offset 160
+// array always starts on a new register.
+    uint v9[2];
+};
+
+RWStructuredBuffer<int> outputBuffer;
+
+__generic<T : IArithmetic, let N : int>
+bool comp(vector<T,N> v1, vector<T,N> v2)
+{
+    for (uint i = 0; i < N; i++)
+        if (v1[i] != v2[i])
+            return false;
+
+    return true;
+}
+
+[shader("compute")]
+[numthreads(2, 2, 1)]
+void computeMain()
+{
+    // CHECK: 64
+
+    outputBuffer[0] = (true
+            && v0 == 1
+            && comp(v1, float3(2, 3, 4))
+            && comp(v2, uint3(5, 6, 7))
+            && comp(v3, uint2(8, 9))
+            && comp(v4, uint2(10, 11))
+            && v5[0] == 12
+            && v5[1] == 13
+            && v5[2] == 14
+            && v5[3] == 15
+            && comp(v6[0], uint3(16, 17, 18))
+            && comp(v6[1], uint3(19, 20, 21))
+            && v7 == 22
+            && comp(v8, uint2(23, 24))
+            && v9[0] == 25
+            && v9[1] == 26
+        ) ? 100 : 0;
+}
\ No newline at end of file